Cooling system for internal combustion engines with liquid cooling



Feb. 18, 1941. F- Nl-FINGER `2,231,939 cooLINa SYSTEM Fon INTmNALcoMBusIIoN ENGINES WITH LIQUID cooLING Filed Aug. 51, 195s Uni/@Irfan-F`RI7"Z NALLJNGER `tormeg/Is Patented-Feb. 18, 1941 UNITED STATES,PATENT .OFFICE COOLING SYSTEM FOB INTERNAL vCOM- BUSTION ENGINES WITHLIQUID COOL- ING Fritz Nallinger, Stuttgart, Germany, assigner toDaimler Benz Aktiengesellschaft, Stuttgart-A Unterturkheim,GermanyApplication August 31, 193s, serial No. 227,613 In Germany September 6,1937 9 claims. (ci. 12s-114) avoid the difilculties due to bad heattransition and to the low speciilc heat of such liquids.

Instead of glycol e. g. also glycerine or mineral oils .are used. y

It has been endeavoured to obtain better results 1o with glycol cooling,by more advantageous feeding ot the cooling medium in the cylinder, byspecial ribs and the like, without such cooling having given fullsatisfaction. The endeavours to avoid the existing disadvantages bysimple means have i5 resulted in that for obtaining a more intensivecooling effect while retaining the ordinary cooling systems, simply thequantity in circulation of cooling liquid, that is of the glycol, hasbeen increased. Such an increase is, however, limited in 20 theradiators because in the case of large circulating quantities theseradiators must be given too large passage cross-sectional areas andconsequently-their degree of ejillciency drops.

These disadvantages are overcome according to 25 the invention in that alarge sized suction and pressure pump maintains the cooling 'liquid inuninterrupted circulation through the cooling spaces of the engine and asecondary circulation is deilected from the suction conduit of the pump30 by which only a portion of the circulating liquid is returned throughthe radiator to the main circulation, so that in the case of smalldimensioned radiator, the largest possible quan-tity of liquid can beconducted through the engine. The par- 35 ticular advantages aretherefore obtained owing to the fact that for the cooling liquid flow,two circulations are provided, one of which effects the circulation ofthe cooling liquid in the engine itself, whereas the other circulation,deected 40 from the first one, conducts a part flow of cooling liquidthrough the radiator of ordinary dimensions. A separate pump or pumpingsystem may be provided for each circulation or also this part ow can bebranched oi! to the radiator through 45 correspondingly dimensionednozzles or pipe conduits. When two pumps viz. pumping systems areemployed, the leed pump eilecting the cooling water circulation in theengine must be larger than the pump viz. pumping system provided for 50the part ilow through the radiator. A large quantity of cooling liquidis conducted through the cooling spaces at a high speed oi ilow by thelarge cooling liquid pump eilecting the internal circulation in theyengine, so that the heat exchange ss between the engine and the coolingliquid is very intensive. For re-coollng the vliquid charged with heat asmaller part ilow is then separated from the main circulation andconducted through the radiator which can consequently be of normaldimensions and have a high degree of efficiency. 5

It is clear that there must be a' certain ratio beg tween the amount ofliquid circulating through the engine and the dimensions of the radiatortoensure a good working of the system, this ratio depending on theaverage amount of heat produced by the engine and the speciiic heat andheat conductivity A`of the liquid used.

Instead of using two pumps viz. pumping systems of dierent sizes, asingle large pump or` pumping system may also be provided which effectsthe circulation in the main cooling ilow andirom which a part ilow isbranched oil to the radiator through suitably dimensioned nozzles orpipe conduits. Instead by means of such a nozzle the amount of liquidcirculating in the part ilow may also be determined by the output of thepump.4 Means to adjust the output of the pump are then provided. Forsuitably regulating the part' ilowthrough the radiator an adjustablethrottle element is preferably tted in the suction conduit.

It is immaterial for the invention whether glycol or some. othersuitable cooling medium, possibly also water with an addition, is used.The essential point is only that a large flow or liquid is conductedthrough the cooling spaces of the engine and that only a part ilowpassesthrough the normally dimensioned radiator, so that --its degree ofeillciency remains within reasonable limits. It is furthermore essentialthat a large and eillcient pump-or two such pumps-are used, viz. pumpingsystems.

Several embodiments of the invention are illustrated by way. 'of examplein the accompanying drawing, in which: 40

Fig. 1 shows a cooling system for internal combustlon engines with twocooling pumps,

Fig. 2 isa similar arrangement with only one cooling pump from whosesuction conduit a part ilow is branched of! to the radiator.

An internal combustion .engine a is equipped with a radiator b and withpumps c and d for the cooling liquid which pumps are driven from themain shaft of the engine for example through the intermediary of bevelwheels q. For the internalv cooling liquid circulation of the engine thelarge sized 4pump c is provided which forces the cooling liquid througha pipe h to the cooling spaces oi the engine and thence sucks it backthrough a pipe i. From the pipe i a pipe m sa cooling temperature isbranches, through which a portion of the cooling liquid is deiiected andreturned by the pump d to the main pressure pipe h through the radiatorb' suction pipe i may be prowith a throttle or shutofl sectional area.Furthermore an adjustable throttle element g may be tted in the suction;pipe i after the point where pipe e branches oil'. The quantity ofliquid owing through the radiator can be accurately regulated by` thisthrottle element g. After pressing through the radiator b the part iiowis returned `throughapipe o to the main ilow, in the pipe i andthencefed by the pump c to the cooling spaces ofthe engine a.

By the cooling system according to the inveni non the not cccling liquidci the main circulation c, h, a, i is repeatedly mixed with the portionof the liquid re-cooled in the radiator b andthus a obtained whichchanges within permissible limits.

Having now particularly described and ascertained the nature of my saidinvention and in what manner the same is to be performed, I declare thatwhat I claim is:

1. A cooling system for internal combustion engines with liquid coolingby means of liquids with bad heat transfer lcomprising a liquid pump oflarge capacity, means to drive this pump, a pipe leading from thecooling spaces of the engine to this pump, a pipe leading from theupperv part of the engine to the suction side of the pump,

a radiator, a pipe leading from the upper part of the radiator to thepipe connecting the upper part oi' the engine with the suction sideofthe pump. a nomle in this part of the pipe system, nally a pipeconnecting the lower part of the radiator with the suction side of thepump.

2. A cooling system for internal combustion engines with liquid coolingby means of liquids with bad heat transfer comprising a pump of largesize, means to drive this pump, a pipe leading from the cooling spacesof the engine to this pump, a pipe leading from the upper part of theconnecting the lower part of the engine to the suction side of the pump,a radiator, a pipe leading from the upper part of the radiator to thepipe connecting the upper part of the engine with thc suction side ofthe pump, a n'o ein this part of the pipe system, nally e, pipe. nectingthe lower part of the suction side of the pump, a throttle element beingprovided in the pipe leading to the upper part of the engine between thepoints where the pipes from the radiator discharge into this pipe.

3. A cooling system for internal` combustion engines with liquid coolingby means of liquids with bad heat transfer comprising a pump oiv largesize, means to drive this pump, a pipe leading from the cooling spaces.of the engine to this pump, a pipe leading from the upper part of theengine to the suction side oi the pump, a radiator, a pipe leading fromthe upper part of the radiator to the pipe connecting the upper' part ofthe engine with the suction side ot the pump, means to adjust the outputof the pump, finally a pipe radiator with tbf.l suction side of thepump.

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radiatorwith the- '4. A cooling system for internal combustion engineswith liquid cooling by means of liquids having low heat transmission,comprising the combination, with a main circulation and a coolerconnectedthereto, of a liquid pump of large 5 `capacity delivering thecooling liquid into the main circulation through the cooling spaces ofthe engine and a second liquid pump of relatively smaller capacity withan auxiliary circulation delivering only a limited part of thecirculating liquid through the cooler to the main circulation, thelimited part of the auxiliary circulation being smaller than theremaining part or the main circulation'.

5. Cooling system for internal combustion engines with liquid cooling bymeans of liquid cool'- ing media with bad heat transfer, comprising twoliquid pumps oi' different output capacities, means -for driving the twopumps, a cooling liquid pipe of large dimensions for the entire coolingliquid comprising a pipe leading lfrom the output por-l tion of acooling chamber of the engine involved to the suction side of the largerpump and a return pipe from the delivery side of said larger pump to thereceiving portion of the 'engine cooling chamber, a smaller pipe for apart of the entire circulating cooling liquid branching oil from thepipe between the upper part of the engine and thesuction side of thelarger pump comprising a radiator, a pipe leading from the branchingpoint on the large pipe of the cooling liquid to the upper part of theradiator, a pipe leading from the lower side of the radiator to thesuction side of the smaller pump and a pipe leading from the deliveryside of the smaller pump to the delivery side of the larger pump, and athrottling member in the suction pipe of the larger pump between thebranching point of the smaller pump and the suction pipe connection ofthe larger pump.

6. A cooling system for internal combustion engines with liquid coolingby means of liquids having low heat transmission, comprising thecombination, with a main circulation and a cooler connected thereto, ofa liquid pump of large capacity delivering the cooling liquid into themain circulation through the cooling spaces of the engine and a secondliquid pump of relatively smaller capacity with an auxiliary circulationdelivering only a limited part of the circulating 50 of said enginelikewise communicating with said 60 cooling spaces, said conduit andcooling spaces forming a closed circuit with one of said pumps includedin said circuit and a throttling member likewise included in saidcircuit, a second closed circuit including a conduit connected at thetwo ends thereof to the ilrst mentionedJ circuit so as to form a shuntcircuit therefor and having the second pump and said radiator includedin said second circuit, said throttling member in the first circuitpositively controlling the flow of liquid not 70- only through the ilrstpump, but also the liquid ilowing through the second pump and theradiator by limiting the ilow in said ilrst circuit.

8. A cooling system according to claim '1, in.' which the outputcapacities of the two pumps are different so that the rst pump has alarger output capacity than the second pump.

9. Ina cooling system for internal combustion engines with liquidcooling by means of 'cooling liquid media having poor heat transfer andhaving pump means and a. radiator, there being means for driving thepump means. the combination of a, conduit connected at o ne end with oneportion of the engine. in communication with the cooling chamberstherein and at the other end with another'portion of said enginelikewisec'o'mmunic'at'ing with said cooling chambers, saidconduit andcooling chambers forming a closed circuit with at least part of the pumpmeans included in said circuit and a throttling member also included insaid circuit, a second closed circuit including a conduit connected atthe two ends thereof to the rst mentioned circuit so as to form a,shuntcircuit therefor and having said radiator included in said secondcircuit, said throttling member in the rst circuit 'positivelycontrolling the ow of liquid not only through the irst circuit, hutalsothe ow of liquid through vthe second circuit and the radiator bylimitingtheiiio'w i said ilst circuit.

. AFRITZ NAILINGER.

